Dynamo-electric machine.



H. F. T. ERBEN.

DYNAMO ELEGTRIG MAUHINE.

APPLICATION FILED FEB.1,1907.

920,846, Patented May 4, 1909.

1 l0 Minn I N 8 6 W1 TA/E' 55175 fA/VENTUR gm HER/MANN 2? z? E'HEEAZ.

A TTY UN ITED ()liiiI-CE.

HERMANN F. '1. ERBEN. ()F Stl-IENECTADY, NEW YORK, ASSIGNOR TU GENERALELECTRIC COMPANY, A (ORIORATION OF NEW YORK.

DYNAMIC-ELECTRIC MACHINE.

Specification of Letters Patent.

Patented May 4, 1909.

Application filed February 1 1907. Serial No. 355,183.

T 0 all whom it may concern:

Be ,it known that I, HERMANN l. T. ERBEN, a citizen of the UnitedStates, residing at Schenectady, county of Schenectady, State of NewYork, have invented certain new and useful Improvements in Dnamo-Electric Machines, of which the fo lowing is a specification.

In certain types of dynamo electric machines it is necessary to rovidemeans at the ends of the rotor core or supporting the end turns orconnections of the rotor coils. In the so-called smooth-core machinesthere is a certain amount of stray flux which passes through thesupporting members for the end turns, 'causin extremely objectionableeddy currents to e set up in such members. Where the sup orting membersare made of solid flange p ates, such as are ordinarily used for this puose, these eddy currents are frequently 0 such magnitude as to seriouslyimpair the efficiency of the machine, as, for example, a machinedesigned to o erate at a high speed.

T e object of my invention is to prevent the losses due to such eddycurrents by sim 1e and inexpensive means and without ma 'ng it necessaryto materially alter the design of the machine or its parts toac'complish this end. I have found that it is possible to prevent theseeddy currents by breakin the conductive continuity of the materia of theend members throughout those portions which are! under the in fiuenceofthe stray field and very good results are obtained by simply slottingthe flanged end lates at numerous points across the angle Formed betweenthe plate and the flange, the slots being arranged in planes parallel tothe axis of the rotor and extending radially therefrom.

My invention will be more. fully understood by the following detaileddescription thereof taken in connection with the accompanying drawingswhich show one embodiment.

In said drawing, Figure 1 is a View partly in side elevation and partlyin cross section of a portion of a machine arranged in accordance withmy invention; and Fig. 2 is a perspective view with a section removed ofone of the end supports.

Referring to t e drawing, l indicates a stator of a direct currentdynamo-electric machine and 2 the rotor which is of the smooth-coretype. a 3 is the core of the rotor. 4 represents one of the rotor coilssupported at its ends upon cylindrical -flanges 5 and 6, which projectlaterally from end-plates 7 and 8 between which the laminae of the coremay be held. The flanged end members, in order t'o secure mechanicalstrength, must be made of metal, that employed being nonmagnetic andusually bronze. All of these parts, together with the construction andarrangement of the pole-pieces 9 of the stator, are, exce t ashereinafter specified, of old and wellmown construction.

In the operation of the machine, there is a sufiicient stray fieldpassing through the meeting portions of the end plates and the tivelylarge eddy currents in the end members. These currents may be broken upby breaking electrically-conductive continuity of the end members inorder that there may be no closed circuits of any considerable length.This breaking up of the end members may be accomplished in various waysand I have found that this may be done with out impairing the mechanicalstrength of these members, by forming a large number of slots 10 acrossthe angle formed between the plates and the llanges extending therefrom.lhese slots may conveniently be arranged in planes parallel to the axisof the rotor and extending radially therefrom. Good results have beenobtained by cutting the slots deep enough only to break the continuitybetween the metal of the plates and of the flanges in the lanes of theslots. If a material stray lie (1 should extend farther from the rotorcore in axial direction, the slots in the flange portions of thesupporting members would of course be lengthened in the 1 axialdirection. Similarly, the slots. in the 5 end plates can be made toextend farther toward the axis in case the distribution of the strayfield should make this advisable. 'lhe slots may be formed in variousways, as by casting the sup orting members with the slots therein or bymaking saw-cuts in the members after they have been cast in solid form.

i W hilc I have illustrated only that form of my invention which Iconsider the simplest and most practical, I do not desire to be flangesto cause the formation of comparelimited to this particular form sinceinits I the angle formed between the plate and the broader aspects myinvention may of course i flange to break the conductive continuity oftake various other forms. 5 the end member, the said slots beingarranged What I claim as new and desire to secure in planes parallel tothe axis of the rotor and 1-3 5 by Letters Patent of the United Statesis: extending radially therefrom.

In a dynamo-electric machine, a rotor, and In Witness whereof, I havehereunto set an end member constructed to form an end my hand this 30thday of January. 1907. support for the coils on said rotor consistingHERMANN F. T. ERBEN. of an end late having a cylindrical flange\Yitnesses: 1 projecting rom its outer edge, said end mem- BENJAMIN B.HULL, er being slotted at numerous points across 5 HELEN ORFORD.

